Searchable encryption scheme supporting dynamic update has become a research hotspot to meet the needs of users for dynamic update of cloud documents. However, most of the known schemes update the index structure by the direct insertion at the tail, which leads to the leakage of the relationship between the newly added keywords and the document. Therefore, this study proposes a dynamic searchable encryption scheme based on semantic grouping. Firstly, the balanced binary tree is constructed as the index structure, and the number of nodes is reduced by semantic grouping for search efficiency improvement. Then, in light of the idea of partition matrix, virtual keywords are added to the matrix to ensure the security of update. Finally, the security of the scheme is analyzed by formal proof.